waste pipe design

I recently purchased an old church that I am converting to a home. It has minimal plumbing and I am trying to design the new waste system. Its in a very small town that doesn't require any permits for plumbing,electrical, or really anything unless you change the footprint of the building. I am doing most of the work myself and want to stick to code as much as possible. After looking over the venting methods in the irc code book and numerous google searches I came up with a crude drawing of what I would like to do. I am looking for any suggestions or obvious problems with this design.

I thought they should be vented but ended up copying examples close to my layout. Do you vent the shower with 2" also?
Do you think venting is needed on the water closets and floor drain as well? would it hurt to do it even if it wasn't required?

The shower, floor drain, and right hand toilet on the first floor are not vented, and the left hand one does not have the right sized vent. If that is a "two sink counter top" you should NOT use a single trap for them. The washer's trap should not be under the floor. The toilet on the second floor is probably not vented if it is actually connected the way you show it. The third floor MAY be done properly, but it depends on HOW you do the piping. The shower drains have to be 2".

O.k. Thanks for the info.
I changed shower drains to 2" and added vents (1.5" ?), the left basement lav WAS a double sink I'm just not sure how to draw it but it will have a trap per sink. Added vent to floor drain (1.5"?). Washer trap is above ground. I thought toilets don't need venting, should they be? (2" vent?).

Currently there is One toilet and one sink in the basement, the rest is what I want to add in the building. the existing toilet and sink will probably be moved so I'm basically starting from scratch and will be having to tie into the existing cast iron stack. The closest plumber is 2hrs and doesn't return calls but I'm up for the challenge.

The don't "need" venting to flush properly, but they do need venting to eliminate "positive pressures" from the water flowing down the pipe from the upstairs bathroom. This is the reason that the basement and first floor toilets NEED venting, which you do not have according to your drawing. In all cases, however, what you actually install will determine how the system works, NOT how you draw it. I have seen many "good" drawings, but the actual installation was completely incorrect.

With positive pressure, the toilets on the lower end of the stack will have water movement in the bowl, every time a toilet above them is flushed.
Sometimes that means that water is slopped around and the water level in the bowl is lowered.

Venting properly is a "good" thing and something we strive for. Done right, all the fixtures can be used without affecting the others.

If I add vents to the toilets does the "drawing" otherwise seem to work?
I will be there this weekend to do some measuring and will work on a layout drawing with the actual fittings and pipe lengths I'll be using.
Thanks for the help so far.